Head actuator having dummy weight used to coincide mass and swing movement centers

Abstract

An object of the present invention is to provide a hard disk drive or related apparatus in which a possibility of head crash can be reduced to minimum even if the apparatus receives an external impact during the operating state. To achieve the object, according to the present invention, in a suspension including a load beam to which a magnetic head slider is to be attached and a head arm continuously joined to the load beam, a dummy weight is attached to the rear end of the head arm, and a attachment position of a joining member for joining a portion including the magnetic head slider, the load beam, the head arm and the dummy weight with a swing portion of a voice coil motor is provided at a position in the vicinity of the center of mass of that portion.

1. A head actuator comprising:
 a magnetic head including a magnetic head slider, a load beam adapted to be attached with the magnetic head slider at one end and a head arm having a swing movement and including a tip end which is joined with the other end of said load beam; and 
 a swing portion of a voice coil motor having a support arm that swingably supports said magnetic head; 
 wherein a dummy weight is attached to a rear end of said head arm, said head arm being joined with said support arm via a joining member; 
 said head arm is biased, at a center of mass of a portion including all of said magnetic head slider, said load beam, said head arm and said dummy weight, in a direction away from said support arm by a pivot pin provided on said support arm, so that said head arm is supported in such a way that it is spaced from said support arm by a predetermined distance with its substantially horizontal state being maintained; and 
 the dummy weight is adapted to make the center of mass of the portion including all of said magnetic head slider, said load beam, said head arm and said dummy weight coincide with a center of the swing movement of said head arm. 
 
   
   
     2. A head actuator according to  claim 1 , wherein said load beam and said head arm are joined in such a way that center lines of said load beam and said head arm in the longitudinal direction coincide with each other, and each of attachment positions of said dummy weight, each of attachment positions of said joining member and each of biasing positions of said pivot pin are respectively arranged to be symmetrical with respect to said joined center lines. 
   
   
     3. A head actuator according to  claim 1 , wherein said joining member comprises an elastic member. 
   
   
     4. A head actuator according to  claim 3 , wherein said elastic member comprises a leaf spring having a U-like shape, a round portion and end portions of said leaf spring are arranged along a center line of said load beam and said head arm in their longitudinal direction, said round portion is secured to either one of said support arm and said head arm, and said end portions are secured to the other one of said support arm and said head arm. 
   
   
     5. A head actuator according to  claim 1 , wherein said load beam and said head arm are constructed as a single member made of a resin. 
   
   
     6. A magnetic recording apparatus equipped with a head actuator according to  claim 1 . 
   
   
     7. A magnetic recording apparatus equipped with a head actuator according to  claim 2 .